Georgians vote on Sunday to elect a successor to strongly pro-Western President Mikheil Saakashvili, who is stepping down after 10 years in power.

The frontrunner is a close ally of Prime Minister Bidzina Ivanishvili, Mr Saakashvili's bitter rival, while the candidate of the incumbent president's party is polling a distant second.

Mr Ivanishvili's win in the parliamentary elections last year ushered in the former Soviet republic's first legal transfer of power. He himself intends to resign within weeks of this vote and leave public office.

What is at stake?

In theory at least, less than last time. Under constitutional amendments passed at Mr Saakashvili's initiative in 2010, much of the presidency's executive powers will be transferred to the prime minister.

The president will formally remain head of state and commander-in-chief of the military, however.

The changes will go into effect after the new president is inaugurated.

Mr Saakashvili already voluntarily ceded most of his political clout to Mr Ivanishvili last year in response to the emphatic election victory of Mr Ivanishvili's Georgian Dream coalition over the president's United National Movement (UNM).

What are the main foreign policy issues?

Since his election, Mr Ivanishvili has tried to mend Georgia's brittle relations with Russia. Ties were formally cut after the two former Soviet allies clashed in 2008 over South Ossetia, a Georgian breakaway region now firmly in the Russian camp.

But Mr Ivanishvili says he shares Mr Saakashvili's aspirations to join Nato and the EU.

Why is Mr Ivanishvili resigning as prime minister?

He says his aim is to wean Georgia off its "Messiah complex" - an alleged tendency to invest unrealistic expectations in a single strong leader.

He cites Mr Saakashvili as a prime example, accusing his rival of falling prey to authoritarianism and corruption after coming to power on a wave of euphoria as leader of the 2003 Rose Revolution.

Some observers think Mr Ivanishvili plans to maintain influence through his as-yet-unannounced successor and the government with newly-enhanced powers that he is leaving in place.

And what about Mr Saakashvili?

Having served two terms, Mr Saakashvili is constitutionally barred from standing again. He says he now wants to work in the Georgian wine industry.

After leading the protests that ousted President Eduard Shevardnadze in 2003, Mr Saakashvili took Georgia down a path of free market reforms and pursued a pro-Western foreign policy, antagonising Russia.

Mr Ivanishvili has indicated that Mr Saakashvili could face questioning or even prosecution over the alleged crimes of his "regime" after his presidential term ends.

Critics say the former academic is bland and uncharismatic. Mr Ivanishvili, who frequently appears with Mr Margvelashvili on the campaign trail, says he was chosen to rid Georgia of its "stereotype" of the "superman" leader.

Mr Saakashvili's UNM has nominated MP Davit Bakradze, 41, as its candidate. Briefly foreign minister in 2008 and parliamentary speaker in 2008-12, he is currently leader of the parliamentary minority.

His campaign has been centred on his opposition to Mr Ivanishvili's softer line towards Russia and purported failure to fulfil campaign promises.

The UNM's popularity has declined significantly since the 2012 vote, and Mr Bakradze's performance will be seen as a test of whether it can remain a political force in Georgia.

Nino Burjanadze, 49, of the small Democratic Movement - United Georgia party, is seen as the only other contender.

Once a supporter of Mr Saakashvili and his pro-Western course, and parliamentary speaker in 2001-08, she became one of his fiercest critics after the 2008 war with Russia.

Ms Burjanadze is now one of the strongest pro-Moscow voices in Georgian politics.

Of the remaining 20 candidates, only Shalva Natelashvili, 55, leader of the populist Labour Party, Giorgi Targamadze, 39, a former TV presenter campaigning for a constitutional ban on same-sex marriages, and Koba Davitashvili, 42, a defector from Georgian Dream, are registering at all in the opinion polls.

What do the polls say?

Opinion polls give Mr Margvelashvili a comfortable lead, but indicate that a second round with Mr Bakradze is a distinct possibility.

One survey - conducted for the US-based National Democratic Institute in late August and early September - gave Mr Margvelashvili 39% support, Mr Bakradze 18% and Ms Burjanadze 7%. The record of polls in Georgia has been mixed, however.

How will the election work?

If no candidate wins more than 50% of the vote, a run-off between the two top-placed candidates must be held two weeks after the results of the first round are published.

Mr Margvelashvili has said he will refuse to stand in a second round, which effectively means conceding the election to the runner-up. He has clarified that he made that statement only out of absolute confidence in a first-round win.

Polling stations open from 0800 to 2000 (0400-1600 gmt). Final results must be published no later than 16 November.

Will it be free and fair?

Past elections were followed by opposition complaints of vote-rigging, but international observers registered only minor irregularities at the 2012 parliamentary vote. In any case, the election was free and fair enough to produce an opposition victory.